Trampoline with adjustable spring tension

ABSTRACT

Springs or other elastic connectors used to support a bed within the frame of a trampoline or the like are attached using methods that permit the adjustment and/or a systematic variation of the tension (or the travel distance required to reach limit of elasticity) between adjacent (or sets of adjacent) springs. These spring attachment methods adjust the energy absorption capacity of the tramnpoline bed, as well as increase the time it takes a given trampoline to absorb a given amount of energy, increasing the shock absorption time and thereby reducing the likelihood of an injury.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to the U.S. provisionalapplication for a “Trampoline with adjustable spring tension” filed onNov. 19, 2004, having serial number 60/629,652, which is incorporatedherein by reference.

BACKGROUND OF INVENTION

The present invention relates to improvements in trampoline, and inparticular, the present invention concerns jumping surfaces used withtrampolines to protect trampoline users from injury, and to provide newuses for trampolines.

In the past, trampolines have been used for a variety of athletic andrecreational purposes. However, thousands of injuries have resulted whenpersons jumping on a trampoline have landed on the rebounding surfacewhile in an awkward or incorrect body position. These “on-bed” injuries,according to some medical studies, represent the majority oftrapoline-related emergency room visits. The U.S. Consumer ProductsSafety Commission (CPSC) reports that in 1999 approximately 110,000people were treated in emergency rooms for trampoline related injuries.Even though this number is half that of play structure/swing setinjuries, some in the medical community have called for a ban on thesale of backyard trampolines. The CPSC and the AAOS have taken a moreresponsible and measured approach to problem. Recognizing that otheroutdoor activities that are more injurious, like bicycling, would fillthe void left by backyard trampoline play, these organizations haveinstead called for safety improvements to help reduce the large numberof trampoline injuries.

One approach to reducing trampoline injuries has been to form a wallaround the perimeter of a trampoline bed so that when a jumper lands toonear the edge, the wall prevents the jumper from falling off. Examplesare shown in U.S. Pat. Nos. 5,399,132 and 6,053,845. However, thesedevices do not directly address injuries that result when users impactthe rebounding surface incorrectly or while in an awkward position. Asecond approach, the use of a harness (worn by the jumper) suspended byelastic cords above the rebounding surface, is an effective way toreduce on-bed, or rebound surface impact injuries. However, suchharnesses are designed for safely teaching users advanced acrobatics onhigh-performance competition trampolines by trained professionals,making them largely inappropriate for low-performance backyardtrampolines that are used almost entirely for basic jumping activitiesand not for advanced acrobatics.

All things being equal, a bed with less tension is more forgiving when ajumper first contacts its surface, it absorbs the impact more slowly andwill thus reduce the severity and quantity of on-bed injuries.Nevertheless, injuries suffered during an impact with the reboundingsurface are still occurring in large numbers on backyard trampoline bedseven though these beds are designed to be less responsive and to haveless initial surface tension than gymnastic grade, competitiontrampoline beds. Reducing bed-impact injuries, especially those thatoccur on backyard trampolines, was the purpose of the present invention,though the art can be used with all trampolines.

Low performance backyard trampolines are used very differently than highperformance trampolines used by skilled competitors for training andcompetition. For instance, many on-bed backyard trampoline injuriesoccur when multiple jumpers are using the trampoline at the same time asreported in the NEISS data compiled by the CPSC. Because children enjoyplaying together most families allow more than one child to jump at thesame time even though this practice is strongly discouraged bytrampoline manufacturers, the CPSC, and others experts. Competitiontrampolines are used almost exclusively in disciplined environments forthe structured teaching of specific skills. In contrast, backyardtrampolines are largely used for fun, unstructured, imaginative playactivities that are relished by kids and recommended by childdevelopment experts who understand that daily physical activitysignificantly enhances learning ability and that kids need activities tocounterbalance today's over-structured and sedentary lifestyles.

Unfortunately, these unstructured trampoline activities generatenumerous on-bed injuries when jumpers land on the rebounding surface inan awkward body position or when a jumper lands on a trampoline bed thathas been preloaded with the energy from other jumper impacts.

There thus remains a need to significantly reduce the quantity andseverity of on-bed injuries that result from such playful activities.Prior trampolines used a rebounding matt that is attached to a frame bya plurality of springs that have a fixed tension. The fixed tension isnot suitable for all users as they very in body weight, age andstrength.

It is therefore a first object of the present invention to provide animproved trampoline with adjustable springs.

SUMMARY OF INVENTION

In the present invention, the first object is achieved by proving atrampoline wherein the springs attach to the frame via an intermediatemember whose length can be varied to modify the spring tension.

The above and other objects, effects, features, and advantages of thepresent invention will become more apparent from the followingdescription of the embodiments thereof taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view showing the trampoline rebounding matt andattachment to the trampoline frame.

FIG. 2 is a perspective view of a trampoline rebounding matt, frame andsprings showing where the spring tension is adjusted along the edge ofthe frame.

FIG. 3 is a cross sectional elevation showing the rotating pin andrelated structure as disposed within the bore trampoline frame.

FIG. 4 is a cross sectional elevation showing the detailed constructionof a first embodiment of the pin in FIG. 3.

FIG. 5 is a cross sectional elevation showing the detailed constructionof a second embodiment of the pin in FIG. 3.

FIG. 6 is an elevation of the pin of FIG. 5 from a viewpoint outside thetrampoline frame, corresponding to section A-A in FIG. 5.

FIG. 7 is an external plan view of an alternative embodiment of the pin.

FIG. 8 is a cross-sectional elevation of the pin of FIG. 7.

It should be understood that FIG. 1-8 are not intended to be drawn tothe same relative or absolute scale, but rather each figure is drawn ata scale to properly display and describe the interrelationship betweenthe elements thereof It being understood that one of ordinary skill inthe art, can readily make adjustments thereto depending on the same andscale of the desired trampoline.

DETAILED DESCRIPTION

Referring to FIGS. 1 through 8, wherein like reference numerals refer tolike components in the various views, there is illustrated therein a newand improved trampoline with adjustable springs, generally denominated100 herein.

Every potential player on a trampoline has a differentstrength-to-weight ratio. Thus, the ability to adjust or tune the systemrebounding response for each player benefits their health and safety. Inthe instant invention the rebounding response it adjusted by varying thespring tension as shown and described below.

The basic operation and configuration of attaching a trampoline mat to atrampoline frame are taught in United States patents and Publishedapplication Ser. No. 6,261,207 (for a Trampoline or the like withenclosure); 6,053,845 (for a Trampoline or the like with enclosure);U.S. patent application Ser. No. 20040121883 (for a Trampoline system);U.S. patent application Ser. No. 2003/0104905 A1 for a Trampoline systemwith plural beds; U.S. patent application Ser. No. 2003/0036460 A1 (fora Trampoline system with adjustable spring elements) and U.S, patentapplication Ser. No. 2002/0137598 A1 (for a Trampoline or the like withenclosure), all of which are incorporated herein by reference.

In a preferred embodiment of the invention the tension in the adjacentor nearby spring alternate as taught in U.S. patent application Ser. No.2003/0036460 A1 (for a Trampoline system with adjustable springelements) such that the springs engage in “stages,” instead of all aonce, making for a softer initial impact. The instant invention providesfor the tension of each spring to be individually adjusted providing afunctionality that allows users to customize the bounce by tightening orloosening the spring connections at the external side of the springframe. This inventive system gives the user control over the feel andperformance during rebounding on the trampoline.

Accordingly, FIG. 1 illustrates in a perspective view a portion of atrampoline system that comprises a circular frame 12 held above theground by a plurality of laterally downward extending legs 60. Therebounding matt or bed 14 is held in tension and suspected within frame12 by coupling to the proximal ends of a plurality of spring, which arein turn coupled to the inside of the circular frame 12 at their distalends. Coupling means a direct or indirect mechanical connection of twomembers.

As shown in more detail in the plan view of FIG. 2, springs 10 and 10′attach to the rebounding matt 14 at a plurality of locations around theperimeter via an intermediate plate 40. Intermediate plate 40 hascentral hole 41 and aperture 45 and 46 on opposite sides of the centralhole 41 that receive fabric loops 51 and 52 sewn, stitched or otherwiseadhered to the rebounding matt 14 at 54 and 53. The hooks like ends ofone or more springs are inserted into central hole 41 to couple thesprings 10 to the rebounding bed 14.

Referring to FIG. 3 it can be seen that the distal ends of the springs10 and 10′ are coupled to the circular frame 12 via pins 20 and 20′respectively. Each of the pins 20 and 20′ have at least one hole or bore21 for receiving the hook like distal end of the spring 10. The pins 20extend through a bore 25 in the circular frame 12. Each pin has a head28 that extends beyond the diameter of bore 25 coupling the pin 20 tothe frame 12, fixing the lateral position of pin 20 with respect toframe 12.

In the preferred embodiment shown in FIG. 3, each pin 20 has a plurality24 of holes 21, 22 and 23 for receiving the hook like distal end ofspring 10. By attaching the distal end of each spring 10 to one of theplurality of holes 24, the spring tension is tunable between two, andpreferably three or more discrete levels. As shown in FIG. 1 thetrampoline frame 12 is supported above the ground by a plurality of legs60.

It is generally desirable to locate and space holes 24 taking intoaccount the stiffness of the springs 10 to be used, such that the middlesetting, hole 22, is the optimal setting for users of average height andweight. Thus, a firmer bounce will be obtained by connecting all springsto the holes 23 most proximal to the trampoline frame 12. Conversely, asofter bounce will be obtained by connecting all springs to the holes 21most distal from the trampoline frame 12

Adjusting the position of the end of springs in a hole selected fromplurality 24 requires the user to pull back a protective pad (not shown)to expose the top ring 12 of the trampoline frame and the periphery ofrebounding matt 14. The user then replaces the protective pad afterselecting a different hole from plurality 24 after tightening orloosening spring connectors before use.

However, in the more preferred embodiments of FIG. 4-6 the springtension can be adjusted while the pad is left in place. In suchembodiments, the tension in each spring 10 is optionally variedcontinuously by adjusting the effective length of pin 20 while it isseated in bore 25. FIG. 4-6 illustrate further details of such pin andrelated mechanisms that permit the continuous adjustment of reboundingcharacteristics of mat 14. The adjustment range of each pin ispreferably at least separation between holes in plurality 24.

In FIG. 4, the pin mechanism 20 is again disposed within a bore 25through frame 12. However, pin 20 has in effect two portions 26 and 27that can be translated relative to each other to shorten or length thepin, that is the distance between head 28 at the distal end of portion26 and hole 21, disposed toward the proximal end of portion 27. Portion26 includes head 28, whereas portion 27 includes the plurality of holes24. Portion 27 has an internal bore 27 a with internal threads 27 b. Theshaft of portion 26 opposite head 28 has exterior threads 26 b thatrotationally engage with threads 27 b of portion 27. Head 28 includes atool receiver opening 29 (for example a slot for a screw driver orhexagonal hole for an allen wrench) such that the corresponding tool canbe used to rotate portion 26 while portion 27 is prevented from rotationby the resistance of spring 10.

FIG. 5 illustrates an alternative embodiment of the invention, shown incross-sectional elevation, in which a spin lock mechanism 30 preventsthe rotation of pin 20 by coupling the head 28 thereof to the frame 12.The spin lock mechanism 30 is a means for preventing the graduallyloosening or movement of the threaded portion of the pin 20 fromvibration. The spin lock mechanism 30 comprises relatively flat plate 38having an inverted “L” shape connected by the narrower edge to the endof circular shaft 35. Note that a portion 38 a of flat plate 38 isconnected to the upper portion of circular shaft 35. The cooperativeengagement of the flat plate 38 within slot 29 of head 28 is alsoillustrated in FIG. 6, which is an orthogonal elevational taken atsection line A-A in FIG. 5. A spring 33 is attached to the other end ofthe circular shaft 35, both of which are in turn disposed with a secondmating bore 34 formed within frame 12. The opposite end of spring 30,which is proximal to the interior of the trampoline, is fixed outside ofbore 34 by end washer 36. Thus, spring 33 urges flat plate 38 inwardtoward frame 12 as it engages the slot 29 in head 28. It is alsodesirable that the upper portion 38 a of flat plate 38 engage thevertical slot 12 a in frame 12. Having flat plate 38 engage both slot 29and slot 12 a securely fixes the relative position of head 28 withrespect to frame 12, thus preventing the unwanted rotation of pin 20(and in particular portion 26 with respect to portion 27) However, whenthe user wishes to adjust the tension of spring 10, flat head 38 isreadily disengaged from slots 29 and 12 a by pulling it forward androtating it 90 degrees. This alternative position for flat plate 38(shown in dashed lines in FIG. 6 and labeled 38′) clears the front ofpin head 38 for receiving a screwdriver tip in slot 29 for rotatingportion 26.

It will be apparent to one of ordinary skill in the art that alternativecooperative structures in frame 12 and pin 20 may be deployed to enablethe lateral translation of holes in plurality 24 to vary the tension inspring 10 continuously. For example, pin 20 need not be formed of twoportions, but may be externally threaded to engage female threads inbore 25. As it is desirable that the portion of pin 20 with theplurality of holes 24 not rotate about the axis of bore 25 when the head28 is rotated to translate pin 20 with bore 25. One embodiment of such apin 20 is illustrated FIG. 7 and 8.

Accordingly, pin 20 has a freely rotating or bearing coupling 70disposed between the portion 77 that includes the proximal end withholes 24 and the portion 76 that includes the distal end having head 28and slot 29. Portion 76 has external thread 72 for engage a threadedcoupling, insert or bore and the like that may be forming in orassociated with frame 12. It will also be apparent that alternativemethods of locking the head 28 of pin 20 are possible.

Further, referring back to FIG. 2, it should be appreciated that it isnot essential to couple a pair of spring 10 and 10′ to a commonconnection on the perimeter of mat 14 using intermediate plate 40. Inalternative embodiments, each of the adjustable springs 10 may beconnected or coupled to a discrete position on the perimeter of the mat14 with a common connection of an adjacent spring. However, it should beappreciated that the embodiment shown and described with respect to FIG.2 is preferred.

While the invention has been described in connection with a preferredembodiment, it is not intended to limit the scope of the invention tothe particular form set forth, but on the contrary, it is intended tocover such alternatives, modifications, and equivalents as may be withinthe spirit and scope of the invention as defined by the appended claims.

1. A trampoline system comprising: a) a rebounding bed, b) a framesurrounding said rebounding bed that is suspended above the ground, c) aplurality of springs spaced about and coupled to said frame at theproximal end and coupled to the rebounding bed at the distal end, d)wherein the proximal end of one or more of said springs is coupled tosaid frame via an intermediate bracket, the radial displacement of saidbracket being variable to adjust the tension of said spring.
 2. Atrampoline system according to claim 1 wherein at least one pairs ofadjacent springs in said plurality of spaced apart springs are couple tosaid rebounding bed at a common junction.
 3. A trampoline systemaccording to claim 1 wherein said bracket comprises a pin seated in abore formed in said frame.
 4. A trampoline system according to claim 3wherein said bracket is laterally displaced by rotation of said pin. 5.A trampoline system according to claim 4 wherein said pin includes afirst and a second concentric segment in mutual threaded engagementwhereby rotation of one concentric segment with respect to the otherconcentric segment increases the effective length of said pin tolaterally displace said bracket.
 6. A trampoline system according toclaim 3 wherein said pin is in threaded engagement within a threadedbore through said frame.
 7. A trampoline system according to claim 6wherein said pin has a freely rotary segment intermediate the connectionwith the bracket.
 8. A trampoline system according to claim 1 whereinone or more of said brackets has a plurality of holes at the distal endthereof for receiving a hook at the proximal end of said spring.
 9. Atrampoline system according to claim 3 wherein one or more of saidbrackets has a plurality of holes at the distal end thereof forreceiving a hook at the proximal end of said spring.
 10. A trampolinesystem according to claim 5 wherein one or more of said brackets has aplurality of holes at the distal end thereof for receiving a hook at theproximal end of said spring.
 11. A trampoline system according to claim1 and further comprising an intermediate plate for coupling said bracketto said rebounding bed.
 12. A trampoline system according to claim 11wherein said intermediate plate is connected to the distal end of two ormore springs.
 13. A trampoline system according to claim 11 wherein saidintermediate plate is connected to the distal end of two or more springsat a central hole therein.
 14. A trampoline system according to claim 11wherein said intermediate plate comprises one or more aperture thatreceive fabric loops connected to said rebounding bed.
 15. A trampolinesystem according to claim 4 wherein said pin can be locked to preventrotation thereof.
 16. A trampoline system according to claim 15 whereinsaid pin is locked by a plate that engages the head of the pin extendingoutward from said frame and a corresponding slot in said frame.
 17. Atrampoline system according to claim 16 wherein said locking plate isattached to the frame is urged to engage in the head of said pin and theslot in said frame by a spring coupled to said frame.
 18. A pin assemblycomprising: a) a first elongated member having one or more holesassociated with the distal end thereof and an internally thread bore onthe proximal end, b) a second elongated member having a threaded distalend for engaging the internally threaded bore of said first elongatedmember, and a laterally extending head at the proximal end, wherein saidhead also comprises a cavity for receiving a tool head such that thesecond elongated member can be rotated with respect to the firstelongated member.
 19. A trampoline system comprising: a) a reboundingbed, b) a frame surrounding said rebounding bed that is suspended abovethe ground, c) an elongated intermediate bracket coupled to said frameat the proximal end and extending inwards towards said rebounding mat atthe distal end, and further comprising a plurality of holes spaced apartfrom said distal end, d) a plurality of springs spaced about and coupledto the periphery of the rebounding bed at the distal end, and attachedto one of the holes in said plurality at the proximal end whereby theradial displacement of said spring by attachment to a different hole insaid plurality varies the tension in said spring.
 20. A trampolinesystem according to claim 19 wherein the radial displacement of saidelongated bracket at the coupling to said frame is variable to adjustthe tension of one or more of said springs without removing theconnected spring from the hole in said bracket.